Protective device for compressors



2 Sheets-Sheet 2 Sept. 6, 1966 F. o. BELLMER PROTECTIVE DEVICE FORCOMPRESSORS Filed April 26, 1965 FIGQQ FRIEDRICH o. BELLMER UnitedStates Patent 3,270,952 PROTECTIVE DEVICE FOR COMPRESSORS Friedrich 0.Bellmer, East Grange, N..I., assignor to Worthington Corporation,Harrison, NJ., a corporation of Delaware Filed Apr. 26, 1965, Ser. No.450,785 16 Claims. (Cl. 230-58) In general, this invention relates to anew and improved protective device for gas compressors and, moreparticularly, to a device which prevents damage to compressors,especially in refrigerant applications wherein damage is often caused byliquid refrigerant entering the compressor during operation.

In a refrigerant system, there occurs, for many reasons, such astemperature and pressure condition changes or the like, the entrance ofliquid refrigerant into the gas inlet of the compressor. If the liquidrefrigerant enters the cylinders of reciprocating compressors or intothe compression chambers of rotary compressors, enormous hydraulicpressure may build up in said chambers causing damage to the affectedcompressor parts. This is due to the incompressability of the liquids.

In the past, conventional reciprocating compressors have used springloaded cylinder heads which will lift up if liquid enters the cylinder.With rotary compressors or other types of compressors with positivedisplacement, a similar liquid relief valve has been used. However,these devices are expensive because they required high loaded springs.For example, in a five-horsepower compressor, the springs must be loadedto 3000 to 4000 lbs. These types of relief members are also noteffective in high speed compressors because of the great inertial massof the cylinder heads and springs which retard the operation of theliquid relief valve thus allowing pressures to build up to dangerousvalues.

Another basic system for preventing liquid from reaching the immediatesuction inlet of a compressor is by utilizing the centrifugal action ofthe circularly directed gas flow around the inside of a cylindricalchamber. This system, however, will not operate if a large amount ofliquid has filled up in the chamber.

Therefore, it is the general object of this invention to avoid andovercome the foregoing and other difficulties of the prior are practicesby the provision of a new and better device for preventing liquid fromentering the gas inlet of a compressor.

Still another object of this invention is the provision of a new andbetter protection device for gas compressors which is inexpensive tomanufacture, simple to install and which will automatically operatewithout regard to the speed of the compressor.

A still further object of this invention is the provision of a new andbetter protective device for a gas compressor which will operate toallow gases to enter the compressor even though small amounts of liquidare initially entrained in the gas as it enters the compressor housing.

Another object of this invention is the provision of a new and betterprotective device for gas compressors which is operative to eliminateliquids prior to their entrance into the gas compressor and which willreturn to normal operating conditions after flooding of the compressorinlet without outside aid.

Other objects will appear hereinafter.

For the purpose of illustrating the invention, there are shown in thedrawings forms which are presently preferred; it being understood,however, that this invention is not limited to the precise arrangementsand instrumentalities shown.

In FIGURE 1, there is shown, schematically, a refrigeration systemutilizing the compressor protective apparatus of the present invention.

3,270,952 Patented Sept. 6, 1966 ice FIGURE 2, is a cross-sectional viewof a compressor built in accordance with the principles of the presentinvention.

FIGURE 3, is a partial enlarged cross-sectional view of the gas inlet tothe compressor before flooding of the compressor housing.

FIGURE 4, is a cross-sectional view similar to FIG- URE 3 after floodingof the compressor housing.

FIGURE 5, is a bottom plan view taken along lines 5-5 of FIGURE 3.

FIGURE 6 is a partial cross-sectional View similar to FIGURE 3 of thesecond embodiment of the protective device for compressors of thepresent invention.

7 FIGURE 7 is a bottom plan view taken along lines 77 of FIGURE 6.

FIGURE 8 is a cross-sectional View of one of the valves utilized in theembodiment of FIGURES 6 and 7 when the compressor housing is notflooded.

FIGURE 9 is a cross-sectional view of the valve of FIGURE 8 when thecompressor housing has been flooded.

In FIGURE 1 there is shown in general form a refrigeration systemgenerally designated by the numeral 10 and including the usual condenser12, evaporator 14, and compressor 16 serially arranged with the outputof the evaporator being connected to the compressor inlet 18 and thecompressor outlet 20 being connected to the inlet of the condenser 12.It would be understood that, in normal operation, it is expected thatthe evaporator will transmit refrigerant vapor to the compressor inlet18.

However, as was stated previously, for various reasons such astemperature and pressure condition changes, liquid refrigerant may reachthe gas inlet 18 of the compressor 16 and enter into the compressor tocause damage thereto.

The compressor 16 comprises a compressor unit 22 driven by a motor 24both mounted within a compressor casing 26. The rotating portion 28 ofthe compressor unit 22 and the rotor 30 of the motor 24 are mounted on acommon shaft 32. The casing 26 is divided into a compressor unit half 34and a motor unit half 36 by a partition 38 having a port 40 connectedbetween the motor unit half 36 and the compressor unit half 34. The port40 communicates with the interior of a compressor unit shell 42 and amotor unit shell 44 on opposite sides of the partition 38. The stator 46of the motor 24 fits suitably within the motor shell 34. Accordingly,gas from the evaporator 14 entering the inlet 18 must pass through thegroove 48 between the shell 44 and stator 46 to enter the passageway 14into the compressor unit half 34. The gas entering the inlet 18 firstcontacts a baffle plate 50 mounted on a wall adjacent to the inlet 18and adapted to deflect gases in a manner whereby the gas will be forcedtangentially about the inner wall of the casing 26 within chamber 36.The gas flow circulating around the inner wall of casing 26 willseparate incoming liquid from the gas. This liquid will tend toaccumulate at the bottom of the chamber 36 and will normally evaporateafter a short time. The gases, including the evaporated liquidrefrigerant then passes through an annular groove 52 formed at the freeend of the shell 44 prior to entering the groove 48. Within the annulargroove 52 there is positioned a suitable washer 54 having a thicknessgreater than the thickness of the passageway 48 for reasons which willbe discussed. The washer 54 rests on pins 56 secured to the shell 44.The washer 54 further provides a very narrow passageway 58 between thestator 46 and the main body of the washer 54 for reasons which willbecome obvious with respect to the discussion of the operation of thecondenser protective system of the present invention.

As was stated, in normal operation, gas enters the inlet 18, impinges onthe curved baffle wall 50 and is directed 3 tangentially along the innerwall of the casing 26 within the motor unit chamber 36. The gas flowcirculating around the inner wall separates incoming liquid from thegas. Any such liquid would then accumulate at the base of the chamber 36and would normally evaporate after a short time. The gases flow upwardlythrough the groove 52 about the washer 54 and through the passageway 48,thus cooling the motor. These gases will be drawn by the compressor unit22 through the passageway 40 and discharged through an opening 60 withinthe compressor unit 22 so that the gases will pass out through theoutlet 20 into the condenser 12.

The weight of the ring 54 and the area of the gap formed between ring 54and the sleeve 44 are chosen in a way that the friction of the passingsuction gas will not lift up the ring 54 from the resting position onthe pins 56.

If the condition arises that, by sudden temperature changes or controlfailure, or by any other reason, a large amount of liquid refrigerantmixed with gas or not, enters into the motor unit chamber 36, saidchamber will first be filled up to the level indicated by the level line62 immediately above the pins 56 without interfering with the compressorperformance. However, at the moment liquid within the chamber 36 risesto a point wherein it fills the groove 52, the ring 54 will lift up fromthe pins 56 by reason of the hydraulic frictional forces thereon toclose the lower openings of groove 48, thus blocking off the liquidfiow. The lifting force acting on the ring 54 caused by the liquid flow,is, as an example, an average of about eighty-five times greater thanthe force caused by the gas flow, due to the ratio of density of gas toliquid refrigerant.

However, to resume normal operation, after the refrigeration system hasbeen stabilized by a conventional process, and no more liquid flows intothe chamber 36, the existing liquid in the chamber has to be broughtback into the system.

During flooding of the casing as shown in FIGURE 4, the existing liquidin the chamber 36 will be vaporized and pumped out by the compressor.This operation is accomplished by the provision of the small gap 58between ring 54 and stator 46. The liquid being sucked through the gap58 will spray out into the passageway 48 and the space between the motor24 and partition 38 within shell 44 where a pressure of almost vacuumexists. This spray will be gaseous as the ring 54 is in the closedposition as shown in FIGURE 4, and the continuous running of thecompressor 28 causes a vacuum in the manner discussed previously and,additionally, the electric motor 24 runs at a high temperature. Thiscombination of high temperature and low pressure cause the vaporizationof the liquid.

If the liquid in the chamber 36 drops by reason of the aboveevaporation, under the level 62, the ring 54 will drop by its ownweight, to the open poistion shown in FIGURE 3 resting on the pins 56.The remaining liquid in the chamber 36 will evaporate completely after acertain time and be pumped out gradually by the compressor.

The gap 58 has, besides serving as a liquid bypass, the special purposeof equalizing the gas pressure over and under the ring 54 when the ringis in the closed position of FIGURE 4 and the liquid has dropped underthe level 62. If the bypass gap 58 was not present, the diflerentialpressure achieved by the evacuation of passageway'48 and the gaspressure in chamber 36 would keep the ring 54 up in the closed positionof FIGURE 4 and restrict further gas flow.

The same type of compressor protection is achieved by the compressor 16'shown in FIGURES 69. In this showing, it will be understood, that primenumerals indicate parts similar to those shown in FIGURES 1-5.

Here again, the compressor includes a motor unit chamber 36' into whichgas is fed through the inlet 18 which impinges on baffle 50. Bafile 50'directs gas tangentially along the inner wall of the casing 26' so as toseparate liquid from the gas. The motor 24' having a stator 46' ispositioned within the shell 44 and formed with a passage 48. The freeend of the shell 44' has vertically positioned valves 64 at spacedpoints about the circumference of the shell 44. In all other ways, theshell 44 is sealed to the outer surface of the stator 46. Thus, gaswithin the chamber 36 can only enter the passageway 48 through thevalves 64. The valves 64, as shown in the open position of FIGURE 8,have an inlet 66 at the lower end thereof and an outlet 68 at the upperend thereof communicating with the passageway 48'; Within each valve 64there is provided a vertically'movable closure member 70 having aconical face 72 and a flat bottom face 74 adapted to rest on a tubularsupport 76. The stem 78 of the actuator 70 telescopes through thetubular support 76 and has an end stop 80 at the bottom thereof. In theopen position, the actuator 70 rests on the tubular support 76 andallows gas to pass between the conical portion 72 and the conical valveseat 82 and, thence, through the outlet 68. The actuator 70 may have alower specific gravity than the refrigerant liquid and, accordingly,when liquid fills the chamber 36 and closes inlet 66, the actuator 70will move upward to the position shown in FIGURE 9 by flotation as wellas bydraulic frictional forces. There, the bottom end stop 80 restsagainst the bottom surface of the tubular support 76 limiting the upwardmovements of the valve actuator 70. The limit of movement of the valveactuator 70 prevents the seating of the valve seat 82 with the conicalface 72 of the valve actuator. This leaves a small gap between theconical face 72 of the actuator 70 and the valve seat 82. Gap 84 issimilar in operation to the gap 58 described with respect to FIGURES 14.That is, the gap 84 allows only minute particles of liquid to passtherethrough when the actuator 70 is in the closed position of FIGURE 9,which liquid when passing between the actuator 70 and the valve seat 82will vaporize as it enters the enlarged passageway 48. Further, when theliquid level has dropped, the pressures above and below the valveactuator 70 are easily equalized by reason of the passageways 84 and,accordingly, the valve actuator 70 will return to the position shown inFIGURE 8.

It will be understood that the valve actuator can have a greaterspecific gravity than the refrigerant liquid and rely mainly onhydraulic frictional forces to lift the actuator into the closedposition.

The present invention may be embodied in other specific forms withoutdeparting from the spirit or essential attributes thereof and,accordingly, reference should be made to the appended claims rather thanto the foregoing specification as indicating the scope of the invention.

I claim as my invention:

1. Apparatus comprising:

(a) a casing,

(b) a motor disposed within said casing,

(c) a shell positioned within said casing about said motor,

(d) said motor being operative to drive means for withdrawing gas fromwithin said shell,

(e) partition means for dividing said casing into two portions,

(f) said motor and shell being positioned in one of said portions ofsaid casing,

(g) said casing having an inlet opening for int-roducing fluid into saidlower portion,

(h) said shell having an inlet opening to allow fluid to pass from saidlower portion into said shell,

(i) valve means at said shell inlet opening operative in a sealedposition thereof to seal said shell inlet opening when liquid iscollected in said shell up to the level of said shell inlet opening,

(j) said valve means including a valve actuator operative to be forcedinto a said sealed position when liquid in said casing reaches the levelof said shell inlet opening.

2. The apparatus of claim 1 including:

(a) bleed means for providing a gas bleed passage between said shellinlet opening and said one portion when said valve actuator is in saidsealed position so as to balance the pressures on opposite sides of saidvalve actuator after the liquid level has dropped below said shell inletopening.

10. The apparatus of claim 1 wherein:

(a) said valve actuator has a specific gravity less than the specificgravity of said liquid collected in said one casing portion.

11. Protective apparatus for a compressor for a refrigerant gascomprising:

(a) a casing, (b) a motor disposed within said casing and having astator and rotor whose common axis is vertically 3. The apparatus ofclaim 2 wherein said bleed pas- 1 isp sed, sage is located adjacent thestator of the motor whereby a cylindrical Shell Positioned Within Saidcasing heat from the motor will vaporize any liquid which about theStator of Said motor, might pass through said bleed passage. (d) saidmotor having a compressor driven by said 4 h apparatus f l i 1 h irotor, said compressor being operative to withdraw (a) said motor isdisposed with the axis of its rotor Tofrigorant gas from Within SaidShell,

in a Vertical Position, (6) partition means for dividing said casinginto an (b) said valve actuator including an annular ring PP? and lowerP resting on a bottom limit stop, (if) sa d motor and shell beingpositioned in said lower (c) said shell inlet opening being positionedim- P P of sald mediately above said annular ring and adapted to be (g)SaI1d compFessol: bemg Posltloned m Sald upper closed by said annularring upon lifting of said Pom,on OfQSmd i annular ring from said bottomlimit stop by reason (h) t casmg hfwmg Inlet opemPg for mtroducmg of therise in liquid level in said one portion. refnge rant gas Into 531dlower P f The apparatus of claim 4 wherein: (i) the inner wall of saidcylindrical shell defining (a) said shell inlet opening is defined by anannular with said stator an inlet opening to allow refrigerant spacebetween the inner wall of said shell and the to Pass from l lower .pomont Sald i outer surface of the stator of said motor, said shell Valvemeans. fi sald Shell opening Operative inlet opening having a thicknessless than the thickm a seal .posltlon. Sald l openmg ness of Saidannular ring, when refrigerant liqu d is collected in said shell to (b)said annular ring having a pass-age on the inner the llwel of Sandshellmlet 9 surface thereof for equalizing pressures on opposite (k).sald valvqmemts mchldmg l actuator 9 sides of said ring when the liquidlevel in said one {lave be .hfted Into Sald Seal Posmon. when hgmdportion has dropped below the level of said Shell in said casing reachesthe level of :said shell inlet inlet opening. openmg l 6. The apparatusof claim 1 wherein said valve actua- (I) gas'hqllld separatlon posmonedzldlwcept t tor includes: said casing inlet opening for separatingliquid (a) a vertically reciprocal member, entra ned in gas passingthrough said casing inlet (b) said vertically reciprocal member havingassozfig q prevent hqmd from entenng sald shell ciated therewith upperand lower limit stops for Th op f l 11 h limiting respectively uppermostposition and lower- 40 appalla O 6 w most Position of Said member, (a)sa d gas-liquid-separat ion means lIlCllldCS a battle,

(c) said uppermost position of said vertically recipro- Sald baijflebemg positioned adjacent Sald casmg cal member being a point immediatelyadjacent said Inlet. i shell inlet opening to define between said shelland (c) Sald casmg mlet oPemng be mg Tjosltomed above said member ableed passageway through which theliwel Shenm1et 9 liquid cannotnormally flow and, through which Sa 1d bflme bemg {P to dlrect gas andgas gas will pass to balance pressures on opposite sides hqfnd mlxtflresenter 1ng Said lower Portion through of said vertically reciprocalmember when the liquid caslflg Inlet openlng against the inner Wall ofSaid level in said one portion of said casing drops below s atFmgEBti-QI manner to Separate liquid the level of said shell inletopening. entrained in said gas and thus aid in preventing liquid 7. Theapparatus of claim 1 wherein: from entering Said Shell inlot p (a) saidmeans for withdrawing gas from within said The apparatus f Claim 11wherein:

1 11 i a compressgr (a) said valve means includes a plurality ofseparate (b) id compressgr b i t d i h th f valve actuators spaced aboutthe periphery of said said portions of said casing on the opposite sideof shell adjacent said shell inlet opening. side partition means fromsaid motor, 14. The apparatus of claim 13 wherein:

(c) said compressor being in communication with the (a) each of saidvalve actuators has an upper and lower interior of said shell by reasonof a passage through li i stop, 531d P (b) said valve actuator upperlimit stop preventing f opp of 9131111 1 mcllldlflgi complete sealing ofsaid shell inlet opening and pro- 2 o I lq tf :i p i ri means WlthlnSald lower P viding in the seal position of said valve actuator a 1 Kcas g, bleed passage for equalizing the pressure above and z gi l g i'ii gzfi ggs e gigjin t hi i i ggg below said valve actuator after liquidin said lower casing inlet p g prior to the p a g if Said position hasdropped below said shell inlet opening.

15. The apparatus of dam 11 wherein: gas through said shell inletopening. p 1 t t 1 9. The apparatus of claim 8 wherein: (a) San va ve acua or comprising an annu ar ring (a) said liquid-gas separation meansincludes a baffle havmg sgeclfic i y less than the 'Speclfic gravltypositioned adjacent said casing inlet opening, of h refngemn? hquldf (b)said bame being operative to direct gas and gas (b) said annular ringhav1ng :ath1ckness greater than with liquid entrained therein, enteringthrough Said the thickness of sa d shell inlet opening to seal saidcasing inlet opening, tangentially against the inner shell Inlet opamngthe Seal Positionwall of said casing within said lower portion to Tho ppof Claim 15 wherein! separate t i d li id f gas prior to h (a) saidshell has an annular groove adjacent the lower sage of aid gas th o h idh ll i l t i edge thereof extending from the lower edge thereof to saidshell inlet opening within which groove is seated said annular ring,

(b) said shell lower edge having integral therewith a limit stop forlimiting the downward movement of said annular ring,

(c) said annular ring having a passageway on the inner surface thereofadjacent the stator of said motor to form a bleed passage when saidannular ring is in the sealed position and further, to cause any liquidpassing through said bleed passage to come into heat exchange relationwith said stator 50 as to vaporize said liquid prior to entry into saidshell inlet opening.

References Cited by the Examiner UNITED STATES PATENTS 11/1929 Frickeyet a1.

9/ 1965 Boettcher 230-207 References Cited by the Applicant UNITEDSTATES PATENTS 2,605,779 8/ 1952 Smithisler, 2,639,671 5/ 1953 Wagner.2,902,044 9/ 195 9 Sherer et a1. 2,908,282 10/1959 Maisch. 3,081,7883/1963 Lewis. 3,082,465 3/1963 Wood.

ROBERT M. WALKER, Primary Examiner.

1. APPARATUS COMPRISING: (A) A CASING, (B) A MOTOR DISPOSED WITHIN SAIDCASING, (C) A SHELL POSITIONED WITHIN SAID CASING ABOUT SAID MOTOR, (D)SAID MOTOR BEING OPERATIVE TO DRIVE MEANS FOR WITHDRAWING GAS FROMWITHIN SAID SHELL, (E) PARTITION MEANS FOR DIVIDING SAID CASING INTO TWOPORTIONS, (F) SAID MOTOR AND SHELL BEING POSITIONED IN ONE OF SAIDPORTIONS OF SAID CASING, (G) SAID CASING HAVING AN INLET OPENING FORINTRODUCING FLUID INTO SAID LOWER PORTION, (H) SAID SHELL HAVING ANINLET OPENING TO ALLOW FLUID TO PASS FROM SAID LOWER PORTION INTO SAIDSHELL, (I) VALVE MEANS AT SAID SHELL INLET OPENING OPERATIVE IN A SEALEDPOSITION THEREOF TO SEAL SAID SHELL INLET OPENING WHEN LIQUID ISCOLLECTED IN SAID SHELL UP TO THE LEVEL OF SAID SHELL INLET OPENING, (J)SAID VALVE MEANS INCLUDING A VALVE ACTUATOR OPERATIVE TO BE FORCED INTOA SAID SEALED POSITION WHEN LIQUID IN SAID CASING REACHES THE LEVEL OFSAID SHELL INLET OPENING.